Catalytic process for the manufacture of unsaturated acids and esters

ABSTRACT

Lower aliphatic acids, e.g., isobutyric acid, and esters, e.g., methyl isobutyrate, are dehydrogenated in the presence of oxygen and a solid heterogeneous dehydrogenation catalyst at temperatures in the range of from about 250*C. to about 600*C. The catalyst is the calcined residue of the mixed phosphates of iron and lead.

' United States Patent [191 Watkins Dec. 17, 1974 CATALYTIC PROCESS FORTHE 3,634,494 1/1972 Tsu 260/486 D MANUFACTURE OF UNSATURATED ACIDS3,770,812 11/1973 Blood .6 260/486 D AND ESTERS [75] Inventor: WindellC. Watkins, Longview, Tex. [73] Assignee: Eastman Kodak Company,

Rochester, NY.

[22] Filed: Oct. 26, 1973 [2]] Appl. No.: 409,823

[52] U.S. Cl 260/486 D, 252/437, 260/526 N [51] Int. Cl. C07c 69/54,CO7c 57/04 [58] Field of Search 260/486 D, 526 N [56] References CitedUNITED STATES PATENTS 3,075,00l l/l963 Godfrey 260/486 D PrimaryEtaminer-James A. Patten Assistant Examiner-P. J. Killos Attorney,Agent, or Firm-Edward R. Weber; Daniel B. Reece, Ill

[57] ABSTRACT Lower aliphatic acids, e.g., isobutyric acid, and esters,e.g., methyl isobutyrate, are dehydrogenated in the presence of oxygenand a solid heterogeneous dehydrogenation catalyst at temperatures inthe range of from about 250C. to about 600C. The catalyst is thecalcined residue of the mixed phosphates of iron and lead.

11 Claims, 3 Drawing Figures SHEET 1 @F CATALYST LIFE STUDY PERCENTCONVERSION and YIELD vs. REACTION TIME COMPARISON of FePO -Pb (POCATALYST to BI'PO4 -FePO -Pb3(P0 CATALYST TEMP.=450 CONTACT TIME=O.32SEC.

D E; FZMQEMQ 205mm 20u hzwomml REACTION TIME, HRS

Pmmwiw H914 3,855,279

sum 2 n5 2 013M P NOISUSANOO .LNHOUHd WHWIXVW 20 mtm 073M P NOISHHANOO.LNHOHEId CATALYTIC PROCESS FOR THE MANUFACTURE OF UNSATURATED ACIDS ANDESTERS This invention relates to the synthesis of unsaturated loweraliphatic acids and esters of such acids by catalytic oxidativedehydrogenation of the corresponding saturated acids and esters.

The catalytic dehydrogenation of the lower alkane acids and their estershas been described in prior art. One known process has been carried outusing a metal oxide catalyst but with no molecular oxygen present duringthe dehydrogenation. In such a process the catalyst is rapidlydeactivated and requires frequent regeneration. Such a process operateswith relatively low conversion per pass which increases operating costsand size of required equipment. See data presented in Industrial andEngineering Chemical Products, Research and Development, Volume II, p.287 (1963) and U.S. Pat. No. 2,945,057. In another known process,dehydrogenation of lower alkane acids and their esters has been carriedout with a metal sulfide oxidizing agent, but again without the presenceof molecular oxygen. In that process the metal sulfide acts as a mildoxidizer which is chemically reduced and requires frequent regeneration.See U.S. Pat. No. 3,370,087.

More recently, U.S. Pat. No. 3,634,494 describes a process wherein thecatalyst consists of the calcined mixed phosphates of iron, bismuth,and, in some embodiments, lead. The catalyst of Pat. No. 3,634,494 givesattractive conversions and yields; however, it suffers from a relativelyshort catalyst life. In addition, the catalyst cannot be satisfactorilyregenerated to its original active save. Therefore, the process of U.S.Pat. No. 3,634,494 loses much of its attractiveness.

Of the many catalytic systems described in the literature, includingthose detailed above, none have all the desirable properties of goodcatalysts. Among the criteria by which a catalyst is judged acceptableare high conversion and yield, long catalyst life and ease ofregeneration to the original activity. 7

Accordingly, one of the objects of the instant invention is to providean improved catalyst giving good conversions and yields and having along catalyst life.

Another object of the instant invention is to provide a catalyst whichcan be easily regenerated to its original activity.

Yet another object of the invention is to provide a catalyst which canbe simply prepared from readily available, inexpensive materials.

These and other objects and advantages of the instant invention willbecome quite clear from the following description, drawings and theappended claims.

In the accompanying drawings, FIG. 1 presents a graphical comparison ofconversion and yield versus time for the catalyst of the instantinvention and the catalyst of prior art patent U.S. Pat. No. 3,634,494.

FIG. 2 depicts the effect of variations in the ratio of wherein R R Rand R are selected from the group consisting of hydrogen and lower alkylgroups containing 14 carbon atoms, is selectively dehydrogenated to thea, B-unsaturated equivalent acid or ester by contacting a gas-feedmixture comprising oxygen and the organic compound with anoxydehydrogenation catalyst comprising iron and lead combined withphosphorus and oxygen, which catalyst can be described nominally as theresidue from the calcined phosphates of the metals. Dehydrogenationoccurs at temperatures of from about 250C. to about 600C., preferablyfrom about 350C. to about 500C. For economy. a preferred pressure forthe oxydehydrogenation is about atmospheric pressure, but the processmay be carried out at pressures in the range of from about 0.3atmosphere to about 10 atmospheres or higher if desired. Water, presentas steam during the reaction, is found to improve the results of theprocess. The ratio of oxygen to saturated acid or ester in the feedmixture is preferably about 0.1 to about 6 gram atoms of oxygen per moleof compound to be dehydrogenated. If desired, the oxygen may be dilutedwith an inert gas such as helium, nitrogen, argon, etc. A preferredsource of oxygen is air.

The catalyst of the instant invention is the calcined residue of amixture of ferric phosphate and lead phosphate wherein the atomic ratioof the metals is defined by 1 Fe/x Pb where x is from about 0.1 to about10. A preferred range for x is from about 0.5 to about 1.5.

The catalyst may be prepared by any of numerous methods suitable toyield the desired mixture of phosphates. In a particularly simplemethod, ferric nitrate enneahydrate and lead nitrate are dissolved inwater and precipitated by the addition of aqueous dibasic ammoniumphosphate. The catalyst is washed, dried, broken into particles of thedesired size and calcined at a temperature of from about 400C. to about600C. Optionally, the catalyst may be pressed into tablets prior tocalcining to get a more convenient catalyst shape.

In apreferred embodiment, the iron-lead phosphate catalyst is obtainedby precipitating the iron-lead phosphates from an aqueous solution oftheir nitrates by the addition of a dibasic ammonium phosphate solution.This yields a final solution pH of approximately 5.5.

It has been found that the calcined catalyst contains more phosphorusthan would be theoretically expected. A typical catalyst, considered asa mixture of iron phosphate plus lead phosphate, would have atheoretical ironzleadzphosphorous atomic ratio of 1:0.6: 1 .4. Byanalysis, the ratio is found to be 110.611 .7-2.3. The phosphoruspresent in excess of the 1.4 ratio may be present as P 0 11 F 0polyphosphoric acid or it may be associated with the metals in someunknown way.

The catalyst may also be prepared by adding phosphoric acid to anaqueous solution of iron and lead nitrates and adjustng the pH to about5.5 by the addition of ammonium hydroxide, Using sodium hydroxideinstead of NH OH results in a catalyst containing sodium which has avery low activity. Other bases, such as methylamine, ethylamine,pyridine, etc., may also be used but are expensive and thus notcommercially attractive.

The pH of the iron-lead nitrate solution should be near 2.0 so that whenthe (Nl-I HPO is added, a final pH of 5-7 is obtained. Adjusting the pHof the iron-lead nitrate solution to a higher value prior to theaddition of phosphate [necessary if (Nl-l.,)l-I PO, is to be used and afinal pH of -7 is desired] causes iron and lead to precipitate as thehydroxides.

Precipitating the iron-lead with (NHQH PQ, followered by the addition ofNH OH to adjust the pH is equally ineffective. Changing the pH after theprecipitate is formed has little or no effect on the catalyst activity,i.e., the activity remains low.

Preferrably the pH of the solution of salts of iron and lead is fromabout 0.5 to about 4.0 (more preferably from about 2 to about 2.5) priorto precipitation, and from about 5 to about 7 following precipitation.

The catalyst may be used in its calcined solid form without support, orit may be used on a catalyst support such as silica, silicaalumina, orsilicon-carbide. The process in which the subject catalyst is usedinvolves the passage of a mixture of the feed-saturated acid or ester,water and air over the catalyst contained in a fixed bed. Thetemperature of the catalyst bed is maintained at from about 250C. toabout 600C, a preferred range being from about 350C. to about 500C., anda more preferred range being from about 400C. to about 450C.

In practice, higher conversions and yields are obtained when severalcatalyst zonesare used with mixing zones separating them. The totalvolume of air is added in portions above each catalyst zone. Most of thework with the catalyst of the invention has been carried out in areactor with two catalyst zones and two air inlet points. The dataobtained in a two-stage reactor can be related to a multistage reactoras has been shown when a three-stage reactor was used in a bench-scalepilot plant to determine catalyst life, scale-up factors, etc.

The reactor effluent is cooled to condense a mixture composed mainly ofwater, unreacted feed acid or ester and product a,,B-unsaturated acid orester. The presence of water in the reactor facilitates the oxidativedehydrogenation reaction but its role in the reaction mechanism isunknown. Optimum concentration of water usually will be in the range of0.5 to about moles water per mole of feed acid or ester. However, up toabout moles of water per mole of acid or ester may be used.

The catalyst of the prior art U.S. Pat. No. 3,634,494 is a mixture ofthe phosphates of bismuth, iron and lead with the metals present in anatomic ratio of 2:l:0.6, respectively. When this catalyst is preparedand used in a two-stage reactor, conversion and yields of isobutyric tomethacrylic acid are in the range of 35 i 5 percent and i 5 percent,respectively. Under identical conditions, the catalyst of the instantinvention, i.e., a mixture of phosphates of iron and lead with themetals present in an atomic ratio of 1:0.6, gives conversions and yieldsto methacrylic acid of i 5 percent and to percent, respectively. Thus,the catalyst of the instant invention is a great improvement over thecatalyst of the prior art. The prior art also teaches that bismuth is anecessary ingredient in the catalyst. Thus, it was quite surprising thata better catalyst could be obtained by the elimination of bismuth. Thecatalyst of the instant invention is a much simpler catalyst than thecatalyst of Us Pat. No. 3,634,494 inasmuch as it contains only two metalcomponents. The instant catalyst is also less expensive since theexpensive component, bismuth nitrate, is not required. Not only is thecatalyst of the instant invention more active than the prior artbismuth/iron/lead catalyst but it also has a longer life and is capableof regeneration through several cycles. Re-

generation is obtained by passing air through the catalyst bed at about450C. to about 550C. without the necessity of removing the catalyst fromthe process reactor. when the catalyst is regenerated in this manner,its activity readily returns to the original high level. In contrast tothis, the three-metal catalyst of U.S. Pat. No. 3,634,494 cannot besatisfactorily regenerated.

This invention is further illustrated by the following examples whichare set forth for purposes of illustration only and should not beconstrued as limiting the invention in any matter.

The reactor used in Examples 1-9 is a 1-inch by 30- inch Vycor tube witha thermowell in the center extending the length of the tube. At the topof the reactor are provisions for feeding air, isobutyric acid, andwater. Another air inlet is positioned 10 inches from the bottom of thetube. Isobutyric acid and water are metered into the reactor through acalibrated pump. The rate of isobutyric acid addition is 40 millilitersper hour and water is fed at such a rate as to obtain the desired waterto isobutyric acid mole ratio. Air is introduced into the reactor at twofeed points through rotameters at such rates as to obtain the desiredoxygen to isobutyric acid mole ratio. Thirty-one percent of the air isfed to the top of the reactor and 69 percent is fed in the center. Two20-milliliter catalyst beds are positioned in the reactor such that thecentral air inlet is between them. The volume between the catalyst bedsand above the upper bed is filled with Vycor chips. The reactor isplaced in an electric furnace and the temperature of the reactor ismeasured and controlled by means of thermocouples in the thermowellwhich are attached to temperature controllers.

The reactor effluent is condensed and collected. Every two hours theeffluent is analyzed by gas chromatography using an internal standardand the conversion and yield are calculated by the following equations.

% conversion (moles MAA in product/moles lBA fed) X yield (moles MAA inproduct/moles lBA fed moles lBA in product) X 100 where MAA methacrylicacid lBA isobutyric acid After the reactor has run for 8 hours, theconversions and yields for all the samples are averaged and reported.The selectivity shown in U.S. Pat. No. 3,634,494 is equivalent to thepercent yield defined above. For comparison, the conversion calculatedby the method used in U.S. Pat. No. 3,634,494 is also reported. Thisconversion, which lprefer to call consumption, is defined by thefolliwing equation.

% consumption (moles lBA fed moles [BA in product/moles lBA fed) X 100Also calculated for each run are water to isobutyric acid mole ratio,oxygen to isobutyric acid mole ratio, and contact time. Contact time (0)is defined by the following equation.

where V volume of catalyst in milliliters V, total gas flow rate at STPin milliliters per second T= reactor temperature in C.

EXAMPLE 1 This example shows the high activity of the catalyst of thisinvention. Also, the ability to regenerate this catalyst isdemonstrated.

To a solution of 323 grams ferric nitrate enneahydrate and 160 gramslead nitrate in 1,500 milliliters water is added 1,500 ml. of an aqueoussolution containing 344 grams dibasic ammonium phosphate. Theprecipitate is removed by vacuum filtration, washed with water, anddried at 120C. for 24 hours. The catalyst cake is calcined 2 hours at500C. then broken into 4-10 mesh particles. These particles are calcinedat 550C. for an additional 2 hours. This catalyst, which has a metalatomic ratio of 1 Fe/0.6 Pb, is placed in the reactor and heated to450C., and the reactants are fed thereto in accordance with theprocedure described above. The following results are obtained over an 8hour period.

Conversion 45.0% Consumption 65.2% Yield 69.1% Water/isobutyric Acid13.3 Oxygen/isobutyric Acid 0.77 Contact Time 0.32 second Conversion45.1%

Consumption 65.3%

Yield 69.0%

EXAMPLE 2 A catalyst is prepared according to the teaching of US. Pat.No. 3,634,494 to show the conversions and yields obtainable with it andits short catalytic life.

A mixture of 40.4 grams ferric nitrate enneahydrate, 97.0 grams bismuthnitrate pentahydrate, and 19.9 grams lead nitrate is dissolved in enough1N nitric acid to make 300 milliliters solution. The salt solution isdiluted to 1,000 milliliters with 1N nitric acid; then, with stirring,1,000 milliliters of an aqueous solution containing 264 grams dibasicammonium phosphate is added, effecting the precipitation of the bismuth,iron, and lead. The precipitate is removed by vacuum filtration,reslurried in 2,000 milliliters water, and refiltered. The filter cakeis dried overnight at l20l40C., broken into 4-10 mesh particles, andcalcined at 550C. for 2 hours. This catalyst, with a metal ratio of 2Bill Fe/0.6 Pb, is placed in the reactor, heated to 450C., and thereactants are fed thereto in accordance with the previously describedprocedure. The following results are obtained over an 8 hour period.

Continued Conversion 34.5% Consumption 76.0% Yield 45.4%Water/lsobutyric Acid 12.0 Oxygen/Isobutyric Acid 0.71 Contact Time 0.31second At the end of this run, the conversion and yield have dropped to29 percent and 35 percent, respectively.

The catalyst is heated to 500C. and air passed through the bed for 16hours. The reactor is cooled to 450C. and another 8 hour run is madewith the following results.

Conversion 29.1% Consumption 82.2% Yield 35.4%

These results illustrate the failure of the catalyst to regenerate toits previous activity.

EXAMPLE 3 This example shows the superior catalytic life of the catalystof this invention as compared to the best catalyst previously known tothe art.

Samples of catalysts prepared by Examples 1 and 2 are tested in thetwo-stage reactor for an extended period of time. The conversion andyield for each catalyst are calculated every 2 hours and are showngraphically in FIG. 1. The catalyst of this invention, i.e., ferricphosphate-lead phosphate, showed no additional loss of activity at theend of a 32 hour period.

EXAMPLE 4 In order to show the wide range of conditions in which thecatalyst of this invention is operable, the water to isobutyric acidmole ratio is varied over a wide range using the catalyst of Example 1.The data thus obtained is shown graphically in P10. 2. This data showsthat the catalyst is most effective in the water to isobutyric acid moleratio range of 8 to 12. In contrast, the catalyst of Example 2 has amaximum at a water to isobutyric acid mole ratio range of 26 to 30. Thisis significant in that the product from the reactor is twice asconcentrated in methacrylic acid when less water is used, thus makingproduct recovery easier and less expensive. Also, with less water, theheat load is reduced. Both factors tend to make the reaction moreeconomical.

EXAMPLE 5 This example shows the effect of changing the composition ofthe ferric phosphate-lead phosphate catalyst on the activity of thecatalyst.

The catalysts are prepared according to the procedure given in Example 1except that the amount of lead nitrate and dibasic ammonium phosphateused is adjusted to obtain the desired iron to lead ratio. The maximumconversion and yield obtained with each catalyst during an 8 hour runare recorded. The data obtained in this manner are shown in FIG. 3.

From the data in FIG. 3, it is apparent that optimum activity isobtained with a catalyst with an iron to lead ratio of 0.5 to 1.5.

EXAMPLE 6 This example shows the effect on the catalytic activity ofcompressing the catalyst of this invention into tablets of a highstrength and more convenient size.

The catalyst prepared according to the procedure given in Example 1 isground into 25-50 mesh particles after drying. These particles aretableted into 4; inch by 4: inch tablets with a crush strength of 4kilograms and calcined at 550C. This catalyst is placed in the reactor,heated to 450C., and the reactants are fed thereto in accordance withthe previously described procedure. The following results are obtainedover an 8 hour period.

Conversion 48.1% Consumption 63.0% Yield 76.4% Water/lsobutyric Acid12.6 Oxygenllsobutyric Acid 0.74 Contact Time 0.32 second The improvedresults obtained with a tableted catalyst are quite unexpected.Generally tableted catalysts give lower conversions and yields whencompared to similar catalysts in the granulated form.

EXAMPLE 7 1n this example the effect on the activity of the catalyst ofthe presence of silica in the catalyst of this invention is shown.

The catalyst is prepared according to the procedure given in Example 1except that 160 milliliters of a 30 percent silica colloid (Ludox AS)are added to the ferric nitrate-lead nitrate solution prior to theaddition of dibasic ammonium phosphate solution. After theprecipitation, the slurry is heated on the steam bath for 3 hours tomake sure that all of the silica is precipitated. After working up thecatalyst as in Example 1, the catalyst granules, with a metal ratio of lFe/0.6 Pb/l Si, are placed in the reactor, heated to 450C., and thereactants fed thereto in accordance with the previously describedprocedure. The following results are obtained over an 8 hour period.

This example shows the activity of a catalyst prepared with phosphoricacid and ammonium hydroxide in place of dibasic ammonium phosphate.

Ferric nitrate enneahydrate (323 g., 0.80 mole), lead nitrate (160 g.,0.48 mole) and 85 percent phosphoric acid (300.5 g., 2.60 moles) isdissolved in enough water to make a 2,300 ml. solution (pH 0.4).Ammonium hydroxide is added with vigorous stirring until the mixturereaches a pH of 5.2. The resultant precipitate is removed by vacuumfrltration, washed with 1,500 ml. water and dried at 140C. The catalystcake is broken into 4-10 mesh particles and calcined for 2 hours at550C. This catalyst is utilized according to the process of Example 1.The following results are obtained over an 8 hour period.

Conversion Consumption Yield Water/Isobutyric Acid Oxygen/lsobutyricAcid Contact Time 2 second similar results are obtained from catalystsprepared by the addition of ammonium hydroxide to a solution of ferricphosphate and lead phosphate so as to bring the pH of the solution intothe range of 4.0 to 7.0.

EXAMPLE 9 Conversion to Acrylic Acid 0.4% Consumption Yield to AcrylicAcid Water/Propionic Acid Oxygen/Propionic Acid Contact Time '5 .32second EXAMPLE 10 This example shows the high level of activityattainable with the catalyst of this invention and the use of thiscatalyst in a benchscale pilot plant unit.

The reactor for this example is made from 2-inch 316 stainless steelpipe with provisions for placing within it three catalyst beds having atotal volume of 525 milliliters. The space between the catalyst beds ispacked with Penn State packing and has provisions for cooling the gasstream. Air inlet points are positioned above the top bed, between thetop and middle beds, and between the middle and bottom beds. Water andisobutyric acid are fed to a vaporizer-preheater and into the top of thereactor. The reactor effluent is condensed and collected. Materialbalances around the reactor system are made every 24 hours by analyzinga composite sample of the product stream collected during this period.

The catalyst, prepared by the procedure given in Example 7, is placed inthe reactor as three equivolume beds and heated to 400C. lsobutyric acidand water are fed to the reactor at rates of 474 grams per hour,respectively, for an isobutyric acid to water mole ratio of 10.0 to 1.Air is fed to the reactor at rates of 1,817, 2,240, and 2,676milliliters per minute from the top to bottom feed points for an oxygento isobutyric acid mole ratio of 0.7 to 1. Under these conditions, thegas streams entering each catalyst bed are adjusted to 390 i 5C. inorder to get a 450C. gas stream exiting each catalyst bed. The resultsobtained with these conditions are as follows.

First Second Third Fourth Fifth Day Day Day Day Day Conversion, 54.255.6 52.3 51.9 49.7 Consumption, 61.6 59.7 56.6 54.7 58.8 Yield, 87.993.1 92.4 94.9 84.5 Space-Time Yield,

g/MMA/liter/hr. 478 492 462 459 438 Although the invention has beendescribed in considerable detail with reference to certain preferredembodiments thereof, it will be understood that variations andmodifications can be effected without departing from the spirit andscope of the invention as described hereinabove.

I claim:

1. A process for making unsaturated acids and esters by dehydrogenationof a compound defined by the formula wherein each of R R R and R isselected from hydrogen and lower alkyl groups containing 1-4 carbonatoms, which process comprises contacting a feed-gas mixture comprisingsaid compound and oxygen at a temperature in the range of from about250C. to about 600C. with a solid catalyst consisting of the calcinedresidue of a mixture of iron phosphate and lead phosphate wherein theatomic ratio of the metals is defined by l Fe/x Pb where x has a valueof from about 0.1 to about 10.

2. A process according to claim 1 wherein x has a valve of from about0.5 to about 1.5.

3. A process according to claim 1 wherein the process is conducted at atemperature of from about 350C. to about 500C.

4. A process according to claim 3 wherein the process is conducted at atemperature of from about 400C. to about 450C.

5. A process according to claim 1 wherein the catalyst is prepared bythe steps of l. preparing a solution of salts of iron and lead,

2. precipitating from said solution a mixture of ferric phosphate andlead phosphate,

3. washing said precipitate,

4. drying said precipitate,

5. adjusting the size and shape of the catalyst particles to thatdesired for process use, and

6. calcining said adjusted particles at a temperature of from about400C. to about 600C.

6. A process according to claiam 5 wherein the solution of salts of ironand lead has a pH of from about 0.5 to about 4.0.

7. A process according to claim 6 wherein the said solution of salts ofiron and lead has a pH of from about 2 to about 2.5.

8. A process according to claim 5 wherein the pH of the solutionfollowing precipitation of ferric phosphate and lead phosphate has a pHof from about 5 to about 7.

9. A process according to claim 5 wherein the precipitation of theferric phosphate and the lead phosphate is accomplished with dibasicammonium phosphate.

10. A process according to claim 1 wherein water is present during thereaction.

11. A process according to claim 10 wherein the water is present to theextent of from about 0.5 moles to about 20 moles per mole of feed acidor ester.

P0-1050 UNITED STATES PATENT OFFICE (5/69) CERTIFICATE OF CORRECTIONPatent No. 3.855.279 D d lgg 12 192! Inventor(s) Windell C. Watkins I:is Certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 1, line 32, delete "save" and insert ---state'---.

Column 3, lines 3 and 4, delete "followered" and insert v---followed---.

Column 4, line 4, delete "when" and insert ---when---.

Column 4, line 54, delete "folliwing" and insert ---following- Column 4,line 63, delete "9 Vc 273/Vg (273 T)" and insert ---9 Vc 273/Vg (273T)--- Column 8, line 13, delete "similar" and insert ---Similar---.

Signed and sealed this 1st day of April 1975.

(JSAL) Attest:

C. l-IARSI-ZALL DANN RU'lh C 2-ZASON Commissioner of Patents AttestlngOfficer and Trademarks

1. A PROCESS FOR MAKING UNSATURATED ACIDS AND ESTERS BY DEHYDROGENATIONOF A COMPOUND DEFINED BY THE FORMULA
 2. A process according to claim 1wherein x has a valve of from about 0.5 to about 1.5.
 2. precipitatingfrom said solution a mixture of ferric phosphate and lead phosphate, 3.washing said precipitate,
 3. A process according to claim 1 wherein theprocess is conducted at a temperature of from about 350*C. to about500*C.
 4. A process according to claim 3 wherein the process isconducted at a temperature of from about 400*C. to about 450*C. 4.drying said precipitate,
 5. adjusting the size and shape of the catalystparticles to that desired for process use, and
 5. A process according toclaim 1 wherein the catalyst is prepared by the steps of
 6. calciningsaid adjusted particles at a temperature of from about 400*C. to about600*C.
 6. A process according to claiam 5 wherein the solution of saltsof iron and lead has a pH of from about 0.5 to about 4.0.
 7. A processaccording to claim 6 wherein the said solution of salts of iron and leadhas a pH of from about 2 to about 2.5.
 8. A process according to claim 5wherein the pH of the solution following precipitation of ferricphosphate and lead phosphate has a pH of from about 5 to about
 7. 9. Aprocess according to claim 5 wherein the precipitation of the ferricphosphate and the lead phosphate is accomplished with dibasic ammoniumphosphate.
 10. A process according to claim 1 wherein water is presentduring the reaction.
 11. A process according to claim 10 wherein thewater is present to the extent of from about 0.5 moles to about 20 molesper mole of feed acid or ester.